The Sunda slow loris (Nycticebus coucang) or greater slow loris is a strepsirrhine primate and a species of slow loris native to Indonesia, West Malaysia, southern Thailand and Singapore. It measures 27 to 38 cm (11 to 15 in) from head to tail and weighs between 599 and 685 g (21.1 and 24.2 oz). Like other slow lorises, it has a wet nose (rhinarium), a round head, small ears hidden in thick fur, a flat face, large eyes and a vestigial tail.

The Sunda slow loris is nocturnal and arboreal, typically occurring in evergreen forests. It prefers rainforests with continuous dense canopies and has an extremely low metabolic rate compared to other mammals of its size. Its diet consists of sap, floral nectar, fruit and arthropods. It will feed on exudates such as gum and sap by licking wounds in trees. The species is generally solitary; one study showed only 8% of its active time was spent near other individuals. Social behavior makes up a very small part of the activity budget, though it has monogamous mating system with the offspring living with the parents. It sleeps during the day, rolled up in a ball in hidden parts of trees above the ground, often on branches, twigs, palm fronds, or lianas. The species is polyoestrous, usually giving birth to a single offspring after a gestation period of 192 days. The young disperses between 16 and 27 months, generally when it is sexually mature.

The species is listed as endangered on the IUCN Red List. It is threatened with extinction due to a growing demand in the exotic pet trade, and has become one of the most abundant primate species on sale at Indonesian pet markets. Its teeth are often pulled out before being sold as pets which can result in infection and/or death, this process makes reintroduction to the wild impossible. It also suffers from habitat loss, which has been severe in the areas in which it is found.